级环境下叶片扩压器流场的实验与数值研究

EXPERIMENTAL AND COMPUTATIONAL INVESTIGATION OF FLOWS IN A VANED DIFFUSER UNDER STAGE ENVIRONMENT

为了研究离心压缩机级环境下的非定常干扰的基本流动现象，并验证多级叶轮机械的 CFD 软件的分析能力，对一大尺度离心压缩机的叶片扩压器流场进行了实验测量和数值计算．实验采用了固定热线、相位锁定——系综平均技术，用常温热线风速仪对叶轮后的叶片扩压器通道内不同周向、径向和轴向位置处的非定常速度进行了测量，同时提出了非定常强度的概念，以定量考核非定常的影响．实验结果表明，叶片扩压器内的非定常流动非常复杂，其时间周期并非叶轮叶片通过时间，随着与离心叶轮之间的距离增大，非定常扰动逐渐减弱，但一直延续到叶片扩压器的出口．另外，对该实验压缩机级开展了两个不同的数值计算，并与实验数据进行了比较：定常数值计算软件采用了作者发展的确定应力模型，非定常数值计算是用商业软件 NUMECA 实现的，计算采用了滑移界面技术．两个计算结果与实验在扩压器的进口截面处吻合得很好．

This paper presents experimental and computational results of flow in a vaned diffuser of a largesize centrifugal compressor stage to study unsteady interactive flows and verify the capability of CFD codes.Detailed instantaneous flow has been measured at several positions using a hot wire anemometer with Phase-Locked Ensemble Averaged technique.To quantitatively describe the unsteady effect induced by the impeller,an unsteady intensity is defined in this paper.The experiment shows that the unsteady flow in the vaneddiffuser is very complex,namely,the unsteady effect decays fast in the vaned diffuser with distance from theimpeller and persists in the diffuser outlet.For this tested centrifugal compressor,the periodic unsteadiness isweaker than the turbulent part in all unsteady flow in the vaned diffuser.Also,two computational investigationsfor the tested centrifugal compressor are performed and compared with corresponding experimental data:oneis a steady method with the deterministic stress model and the other is an unsteady method with the slidinginterface technique.Both numerical results are shown in good agreement with the experiment in the inlet planeof the vaned diffuser.